# Non-coding RNA regulation of Myeloid Cells

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 2024 · $483,706

## Abstract

PROJECT
SUMMARY
Tumor-Associated
immune
 Macrophages (TAMs) are a metabolically and functionally heterogeneous population of
cells that play critical roles in both anti-tumor immunity and tumor growth.Importantly, the type of TAM
infiltrate within a neoplasm has been shown to be a prognostic factor for tumor growth and sensitivity to cancer
immunotherapies. Hence, elucidating the mechanisms that determine the differentiation of pro-tumor and anti-
tumor TAMs within the tumor microenvironment (TME) can lead to novel therapeutic approaches. For nearly 40
years, it has been known that inhibition of the mitochondrial electron transport chain (ETC), which is composed
of five multiprotein complexes, is critical for the anti-tumor activity of TAMs. However, the mechanisms by which
the activity of the ETC is controlled in TAMs and how this process determines the functions of these immune
cells within the TME are largely unknown. Interestingly, the terminal enzyme of the ETC, Complex IV (CIV), is
the only ETC complex in which its core protein subunits are replaced by closely related isoforms to tune its
activity in response to signals from the tissue microenvironment. Using single-cell transcriptomics and 7 novel
mouse strains that we generated, we demonstrated that type I and II interferons (IFNs) potently induce a single
transcript encoding the peptide NDUFA4L3 and the microRNA miR-147 in human and mouse TAMs from
melanoma tumors. Notably, we also showed that NDUFA4L3 and miR-147 work in concert to remodel CIV
protein subunit composition in TAMs through the degradation and subsequent replacement of a core component
of CIV, NDUFA4. Importantly, NDUFA4 degradation as a result of NDUFA4L3 and miR-147 induction by IFNs,
or its genetic deletion, blocks tumor growth and leads to a dramatic accumulation of anti-tumor TAMs. Therefore,
we hypothesize that regulation of CIV subunit composition and activity in TAMs through the induction of
NDUFA4L3 and miR-147 by IFNs is a key evolutionarily conserved metabolic checkpoint by which TAM
differentiation is controlled, which could be targeted in the context of cancer immunotherapies. Thus, in aim 1 of
this project, we will use two novel conditionally knock-out strains for NDUFA4 and NDUFA4L3 that we generated,
single-cell and spatial transcriptomics, and the humanized mouse MISTRG-6 that supports the development of
human TAMs, to establish how CIV subunit composition in TAMs regulate anti-tumor immunity and responses
to checkpoint blockade inhibitors. In aim 2, we will use a molecular model of CIV with an atomic resolution that
we generated, metabolomics, and novel technologies to measure cellular metabolism and mitophagy rates at
the single cell level to determine how CIV protein subunit composition and its activity contribute to the metabolic
and functional states of TAMs. As recent reports demonstrate that macrophages from patients with loss of
function mutations in NDUFA4 show a striking pro-inflammatory gene sign...

## Key facts

- **NIH application ID:** 10991136
- **Project number:** 1R01CA294364-01
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Jorge Henao-Mejia
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $483,706
- **Award type:** 1
- **Project period:** 2024-07-01 → 2029-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10991136

## Citation

> US National Institutes of Health, RePORTER application 10991136, Non-coding RNA regulation of Myeloid Cells (1R01CA294364-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10991136. Licensed CC0.

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